13
x12
——-
26
+130
——-
156
So first you do the back of 12, 2 times the back of 13, which is 6. Then the back of 12, 2 times the front of 13, which is 2. So you get 26. Then you go to the next line and put a zero, then the same thing as you did with the back of 12, but with the front, which is 1. So 1 times 3 and 1 times 1, so you get 13 and the zero you added earlier, 130. So you get 26 and 130, add them to get 156.
